Excavator teeth

ABSTRACT

An excavator tooth system having a mounting nose having a projecting spigot and a wear member ( 12 ) having at one end a socket ( 18 ), the socket ( 18 ) being defined by spaced side walls and upper and lower walls converging from a rearwardly facing socket opening to a forward end of the socket. Each of the upper and lower walls comprises a forward bearing face ( 8   a ) and a rear bearing face ( 7   a ) separated by a forwardly convergent intermediate face. The front and rear bearing faces ( 8   a,   7   a ) are substantially parallel to a longitudinal axis ( 50 ) of the wear member and engage corresponding bearing faces ( 8,7 ) in said spigot.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of pending U.S. applicationSer. No 10/707,290, filed Dec. 3, 2003.

FIELD OF THE INVENTION

This invention is concerned with improvements in excavator teeth forearth excavating devices.

The invention is concerned particularly, although not exclusively, withthe mounting of excavator teeth adaptors to adaptor noses on anexcavating device such as an excavator bucket or the like.

BACKGROUND OF THE INVENTION

Excavating teeth mounted to the digging edge of excavator buckets andthe like generally comprise a replaceable digging point, an adaptor bodyand an adaptor nose which is secured by welding to or is otherwiseintegrally formed with the digging edge of an excavator bucket. Theadaptor has a socket-like recess at its rear end to receivably locate afront spigot portion of the adaptor nose and a locking pin extendsthrough aligned apertures in the adaptor and nose to retain the adaptorin position.

In use, excavator teeth are subjected to extensive load forces along alongitudinal axis of a tooth as well as in vertical and transversedirections. A snug fit is required between the digging point and thefront portion of the adaptor and also between the adaptor socket and thenose spigot portion and their respective mounting pins to avoidpremature wear between the components. As the various components wear,the locking pins can loosen thereby increasing the risk of loss of adigging point or an entire digging tooth assembly.

The greatest loads experienced by excavator teeth are vertical loadswhich tend to generate large moment forces capable of rotating a toothoff the front of an adaptor and/or rotating the adaptor off the adaptornose.

Despite many prior art attempts to improve the mounting of an adaptor toa nose, most of these proposals suffer from one or more deficiencies.

U.S. Pat. No. 4,182,058 describes an excavator tooth having a rearwardlydivergent tapering socket to receive a nose having acomplementary-shaped front spigot portion. Resistance to rotationalmoment forces is borne by a resilient steel cotter pin extending throughaligned vertical apertures in the socket and spigot portions.

U.S. Pat. No. 3,023,521 also describes an excavator tooth having arearwardly divergent tapering socket to receive a complementary-shapedtooth support spigot portion. Rotational moment forces are resisted by alip engaging in a recess in the tooth support member.

U.S. Pat. Nos. 3,774,324, 4,338,736, 4,481,728 and 4,903,420 alldescribe nose and tooth combinations wherein the nose has a generallyconvergently tapering spigot portion with a forward tip having abox-like configuration with at least the upper and lower surfacesthereof having faces parallel to each other and to a longitudinal axisof the nose portion. With the exception of U.S. Pat. No. 4,338,736,which describes a transverse locking pin, each of the tooth mountingarrangements is heavily reliant on a large vertical locking pin toresist rotational moment forces tending to rotate the teeth offrespective noses.

U.S. Pat. No. 4,231,173 describes a tapered adaptor nose having abox-like free end, which engages in a mating box-like socket cavity toresist rotational moments. Opposed pairs of rearwardly extending tonguesengage in corresponding recesses in the outer surfaces of the adaptornose to resist rotational movements. Because the tongues themselves areunsupported, they possess a limited capacity to resist rotational momentforces.

U.S. Pat. No. 5,272,824 describes a structure similar to that of U.S.Pat. No. 4,231,173 except that the side tongues are of more robustdimensions and the upper and lower tongues are formed as box-likemembers with apertures to receive a vertical mounting pin passingthrough aligned apertures in the tooth and adaptor nose.

U.S. Pat. Nos. 3,196,956 and 4,404,760 provide flat rail surfaces on theadaptor nose to engage with mating grooves in the socket aperture of acorresponding tooth. In the case of U.S. Pat. No. 3,196,956, the matingrail and groove surfaces are forwardly tapered, whereas in U.S. Pat. No.4,404,760 the mating rail and groove surfaces are generally parallel tothe longitudinal axis of a tooth.

U.S. Pat. No. 5,423,138 describes a generally tapered nose having abox-like front end with upper and lower transverse surfaces generallyparallel to a longitudinal axis of a tooth. The parallel upper and lowertransverse surfaces are contiguous with upper and lower rail surfaces oneach side of the nose and parallel to the longitudinal axis of thetooth. A pair of rearwardly extending side tongues locate in recessesformed in the outer side faces of the nose, ostensibly to resistrotational moment forces in the tooth. Because the side tongues arerecessed to accommodate the side rail portions, the robustness of theside tongues is somewhat compromised

U.S. Pat. No. 4,233,761 describes a fairly stubby tapered nose having abox-like front portion with upper and lower surfaces generally parallelto a longitudinal axis of an excavator tooth, an intermediate rearwardlydiverging tapered portion and a rear portion having upper and lowersurfaces extending generally parallel to a longitudinal axis of thetooth. Formed on the upper and lower surfaces of the front, intermediateand rear portions of the nose are spaced parallel reinforcing ribs whichare located in mating grooves in the excavator tooth. A large verticallocking pin extends through aligned apertures in the tooth and nosebetween the reinforcing ribs. This structure is heavily reliant on thelocking pin to resist rotational moment forces however it is consideredthat this configuration may be prone to failure in the rear portion ofthe adaptor.

U.S. Pat. No. 5,709,043 describes a nose/adaptor combination wherein theadaptor socket tapers convergently towards a box-like front portionhaving upper and lower bearing surfaces generally parallel to alongitudinal axis of the tooth, a front transverse upright bearingsurface and rearwardly divergent bearing surfaces formed at obtuseangles between the converging upper and lower walls and the side wallsof the socket, ostensibly to avoid areas of stress concentration.

U.S. Pat. No. 6,018,896 describes a pin/retainer system for locking anexcavation tooth onto an adaptor wherein the retainer is inserted in theadaptor and a wedge-shaped pin is driven into aligned apertures in thetooth and adaptor to resiliently engage with the retainer.

United States Publication No US 2002/0000053A1 describes a mechanism forreleasably retaining an adaptor into the nose of a bucket lip or thelike wherein a tapered threaded socket is non-rotatably located on theinside of an aperture in the side wall of the adaptor. A threadedretaining pin extends through the threaded socket and locates in analigned aperture in the bucket nose.

U.S. Pat. No. 5,337,495 describes a tooth point slidably locatable overa tapered adaptor front portion, the tooth point being releasablysecured on the adaptor by a pair of cap screws extending throughapertures in the side walls of the tooth into threaded inserts locatedin recesses on opposite sides of the adaptor front portion. The insertshave a shouldered face and a curved face nestable incomplementary-shaped adaptor recesses to prevent rotation when the capscrews are threadably located therein.

U.S. Pat. No. 5,172,501 described attachment of a digging point to anadaptor by a threaded bolt extending through an aperture in a point forthreaded engagement in a threaded opening in the adaptor. Otherretention systems for digging points on adaptors or adaptors on nosesare described in U.S. Pat. Nos. 6,119,378, 6,467,204, 6,052,927 and6,467,203.

Other devices for removably securing replaceable wear elements on earthworking equipment such as a retaining pin, a bolt, a pin lock, a spooland wedge system or a flex pin are described in U.S. Pat. Nos.3,839,805, 3,982,339, 4,587,751 and 5,716,667 respectively.

U.S. Pat. No. 5,937,550 describes a lock assembly for releasablysecuring an adaptor to a nose of an excavator support structure. Thelock assembly comprises a body and a base coupled together and adaptedfor insertion, while coupled together, in a hole in the nose of thesupport structure. The length of the lock assembly is extended to securethe adaptor and is retracted to release the adaptor. While adequate forsecuring an adaptor to a nose of an excavator support structure, thelock described in this patent is relatively complex in design andoperation leading to high costs and labour intensive extractionprocedures in the field.

Canadian Patent Application No 2,161,505 describes a system forremovably retaining an excavation point on an adaptor with at least oneflanged sleeve having a screw-threaded aperture therein, the flangedsleeve being non-rotatably locatable in a transverse bore in the adaptorbefore fitment of the point onto the adaptor. A screw-threaded pin isinserted into the sleeve via an aperture in the point whereby portion ofthe head of the pin retains the point on the adaptor.

U.S. Pat. No. 6,708,431 discloses an excavator tooth system comprising amounting nose and an adaptor for removable attachment thereto byengagement between a spigot-like projection on the mounting nose and asocket-like recess in the rear portion of the adaptor. The mounting noseis described as having a horizontally elongated elliptical cross-sectionalong its length and the tapered tip of the nose is shown as havingcrescent shaped upper and lower front bearing surfaces which lieparallel to each other. The rear bearing surfaces of the mounting noseare formed as longitudinally and transversely arcuate surfaces taperingconvergently towards the tapered tip of the nose. The socket-like recessin the adaptor has internal wall surfaces generally complementary to thecontours of the mounting nose and there is a snug fit between the frontand rear bearing surfaces of the mounting nose and complementaryinternal contours of the adaptor.

While generally satisfactory for their intended purpose, theabovementioned prior art adaptor/nose combinations all suffer from oneor more shortcomings or disadvantages in terms of inadequate resistanceto rotation of an adaptor off a nose under the influence of verticalloads applying a rotational moment to the adaptor, a predisposition topremature wear, difficulties in retention of the adaptors on noses,inadequate locking systems and unduly complicated configurations givingrise to increased fabrication costs.

It is an aim of the present invention to overcome or alleviate at leastsome of the abovementioned prior art disadvantages or otherwise toprovide consumers with a convenient choice.

SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided an excavatortooth system comprising:

-   -   a mounting nose having a projecting spigot; and,    -   a wear member having at one end thereof a socket, said socket        being defined by spaced side walls and upper and lower walls        converging from a rearwardly facing socket opening to a forward        end of said socket, each of said upper and lower walls        respectively comprising a planar front socket bearing face and a        planar rear socket bearing face separated by a forwardly        convergent intermediate face, said front and rear socket bearing        faces being substantially parallel to a longitudinal axis of        said wear member, said mounting nose having complementary planar        front and rear spigot bearing faces on upper and lower surfaces        thereof, said front and rear spigot bearing faces being        substantially parallel to a longitudinal axis of said mounting        nose and, in use, snugly engaging with said front and rear        socket bearing faces when said wear member is located on said        mounting nose.

Suitably, said forward end of said socket forms an end bearing face.

If required, said end bearing face may extend transversely of saidlongitudinal axis.

The wear member may comprise an excavator tooth having a digging edge ata front end thereof.

Preferably, the wear member comprises an adaptor having a front endadapted for releasable attachment of a digging point.

Suitably, said wear member includes an aperture in at least one wall ofsaid socket.

Preferably, said wear member includes aligned apertures on oppositewalls of said socket.

If required, said aligned apertures may extend through upper and lowersocket walls.

Preferably, said aligned apertures extend through opposite side walls ofsaid socket.

If required, at least portion of said rear bearing face is of a widthgreater than said forward bearing face.

At least portion of said rear bearing face may be of substantially asimilar width to said forward bearing face.

Suitably, said rear bearing face is of an area greater than said forwardbearing face.

The socket opening may have a transverse width greater than the width ofthe forward end of said socket.

If required, the side walls of said socket may taper convergentlytowards said forward end of said sockets.

Alternatively, the side walls of said socket may be stepped.

According to another aspect of the invention there is provided anexcavation device having an excavator tooth system according to a firstaspect of the invention and wherein said mounting nose is integrallyformed with said excavation device.

Alternatively, said mounting nose may be attached to said excavationdevice.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more fully understood and put intopractical effect, reference will now be made to the accompanyingdrawings in which:

FIG, 1 shows portion of an adaptor nose;

FIG. 2 shows an exploded view of an excavator tooth system according theinvention.

FIG. 3 shows schematically an upright cross-sectional view showing theengagement between a mounting nose and an adaptor according to theinvention.

FIG. 4 shows in transverse cross-section a locking pin for releasableattachment of the adaptor to the mounting nose;

FIG. 5 shows in transverse cross-section the locking pin of FIG. 4 in alocked position;

FIG. 6 shows schematically a transverse cross-sectional view of anexcavator tooth system according to one aspect of the invention;

FIG. 7 shows a lip for an excavation device which is adapted inaccordance with the invention;

FIG. 8 shows an exploded view of the lip of FIG. 7 and excavator teethsystems;

FIG. 9 shows the arrangement of FIG. 8 in an assembled state;

FIG. 10 shows a lock for releasable attachment of the adaptor to themounting nose;

FIG. 11 shows a longitudinal cross sectional view of a retaining memberof the lock of FIG. 10; and

FIG. 12 shows a longitudinal cross sectional view of a body member ofthe lock of FIG. 10.

DETAILED DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, for the sake of clarity, like referencenumerals are employed for like features where appropriate.

In FIG. 1, the mounting nose 1 is shown as integrally formed with acutting lip 2 of an excavation device such as a dragline bucket or thelike (not shown).

Nose 1 includes a pair of opposed tapered forwardly convergent sidefaces 3, a front face 4 and upper and lower faces 5,6 converging towardsfront face 4. Upper and lower faces 5, 6 each include planar rearbearing faces 7 and planar forward bearing faces 8 separated by atapered generally planar intermediate face 9. Rear bearing faces 7,forward bearing faces 8 and front bearing faces 10 are all shown asshaded regions for the sake of clarity. Side faces 3 may be tapered atan angle of from 8° to 15° degrees relative to a longitudinal axis X ofthe mounting nose. Preferably, side faces 3 are tapered at about 11° tolongitudinal axis X.

Rear bearing faces 7 are parallel to each other as are forward bearingfaces 8. Each of rear and forward bearing faces 7,8 are also parallel tolongitudinal axis X of the mounting nose 1.

Extending transversely of mounting nose 1 is an adaptor mountingaperture 11. Aperture 11 is generally oval in cross-sectional shape withthe longer oval axis extending generally parallel to nose axis X.Aperture 11 is positioned closer to top face 5 than bottom face 4, thepurpose of which positioning will be described in detail later.

In a conventional tapered wedge-shaped adaptor nose there is asubstantial rotational moment to a digging point in the region of theadaptor tip. This rotational moment force is resisted by normallydirected forces in the rear of the upper and lower wedge faces andfrictional forces in the upper wedge face. If the rotational moment issmall compared with the normally directed forces on the upper wedgeface, the frictional forces produced by the normally directed forces canbe sufficient to withstand the rotational moment. For a digging pointthis usually is the case because as the moment force on the diggingpoint is applied almost directly above the upper face of the wedge, themoments are small compared to the normal forces and the correspondingfrictional forces are sufficient to retain the digging point in place.

In the case of the mounting between a wedge-shaped or tapered adaptornose and the adaptor itself, the frictional forces are insufficient towithstand the rotational moment to prevent the adaptor from simplyrotating off the nose under load. To overcome this it is customary withwedge-shaped adaptor noses to employ a substantial pin to retain theadaptor in place as the pin must withstand very large forces appliedthereto. Typically, this necessitates a vertically oriented pin.

In the present invention, the key bearing faces are configured to begenerally planar and parallel to the longitudinal axis of a wear membersuch as an adaptor. The wear member is thus cantilevered on the nosewhereby the rotational moment is resisted by the high load forcesapplied to the upper forward bearing face and the lower rear bearingface. Generally speaking the higher those load forces, the higher thefriction available to hold the adaptor or wear member onto the nose.Because the bearing faces are substantially planar and parallel, anadaptor cannot rotate off its nose.

The excavator tooth system according to the invention in effect becomesself-locking by virtue of its high internal frictional forces. As aconsequence, the role of the retaining pin is substantially reduced frombeing a major structural component in prior art systems to being adevice which simply stops the wear member from falling off a nose.

FIG. 2 shows an exploded view of an excavator tooth assembly accordingto one aspect of the invention.

As shown, the assembly comprises a mounting nose 1 (shown partially), anadaptor 12 and a replaceable digging point 13.

Adaptor 12 includes a hollow recess or socket (not shown) to receive thenose 1. Adaptor 12 is retained on nose 1 by a spool and wedge pin 14which extends through oval-shaped apertures 15 in the adaptor body whenaligned with aperture 11 in nose 1. Point 13 is releasably retained onthe front tip of adaptor 12 by a retaining pin (not shown) extendingthrough aligned apertures 16,17 in the point 13 and adaptor 12respectively.

FIG. 3 is a schematic vertical cross-sectional view through the nose 1and adaptor 12 of FIG. 2 and shows the engagement of the planar parallelbearing surfaces of the nose and adaptor.

When the spool and wedge pin 14 is tensioned nose 1 is firmly located inthe socket cavity 18 of adaptor 12 with the front bearing face 10 ofnose 1 in abutment with corresponding bearing face 10 a in adaptor 12.Similarly, rear and forward bearing faces 7 and 8 are abutted againstcorresponding bearing faces 7 a,8 a respectively in adaptor 12.

FIG. 4 is a partial schematic transverse cross-sectional view throughthe nose/adaptor combination shown in FIG. 3.

As shown, spool and wedge retaining pin 14 is in an extended unlockedposition with the shoulders 20 of pin body 21 being located behind therear inner edges of apertures 15. A threaded bolt 22 is rotatablyjournalled in one end of pin body 21 and its other end is engaged in athreaded aperture 23 in wedge member 24. As bolt 22 is rotated, it drawswedge member 24 into the aligned apertures 15,11 of adaptor 12 and nose1 respectively until it wedges adaptor 12 into tight engagement withnose 1 as shown in FIG. 5.

As can be seen in FIG. 5, retaining pin 14 is in a retracted lockingposition with the free ends thereof slightly recessed into apertures 15.

FIG. 6 shows a schematic transverse cross-sectional view through theassembly of FIG, 2 when in an assembled state.

FIG. 7 shows another aspect of the invention.

Depicted is a cutting lip 30 of an excavation device such as a draglinebucket (not shown).

Cutting lip 30 is cast as an integral component from a suitably wearresistant metal alloy and comprises a transverse cutting bar 31, cheekplates 32 and mounting noses 1 at spaced intervals therealong.

Noses 1 are faired back into cutting bar 31 forming recessed regions 33between adjacent noses. At the front portion of each cheek plate 32 aremounts 34 for attachment of replaceable cutting edges (not shown).

FIGS. 8 and 9 respectively show an exploded view and an assembled viewof the cutting lip 30 of FIG. 7 with adaptors 12 and digging points 13of FIG. 2.

In the assembly of FIG. 9, lip shrouds 35 are removably secured in therecessed regions of bar 31 to minimize wear on the lip assembly. As canbe seen from FIG. 9 and also from FIGS. 1 and 3, the aligned pinapertures 11,15 of nose 1 and adaptor 12 respectively are displacedvertically upward relative to a transverse plane occupied by thelongitudinal axis X as shown in FIG. 1, which axis lies in a centralplane of nose 1. By having the mounting apertures offset from a centralposition, the retaining pins can be removed or installed without needingto remove the lip shrouds 35. In turn, this permits the face of the lipshroud 35 to be located at its optimal position with the face of theshroud running along the centre line of the tooth assembly.

It readily will be apparent to persons skilled in the art that manyvariations and modifications may be made to the invention withoutdeparting from the spirit and scope of the invention.

For example, as the key digging forces are taken up by the socket andspigot fitting between the nose and the wear member or adaptor; theretaining pin can be of any design as it functions merely to hold thewear member in place on the nose and otherwise does not constitute aload bearing member.

FIG. 10 shows lock 36 being an alternative embodiment of a locking pin.

FIG. 11 shows a longitudinal cross sectional view of the retainingmember 38 illustrated in FIG. 10.

FIG. 12 shows a longitudinal cross sectional view of the body member 37of FIG. 10.

As shown in FIGS. 10 to 12 the locking pin 36 comprises a body member 37wherein the body has an oval shaped cross section of substantiallyidentical configuration as the cross sectional shape of aperture 11 inmounting nose 1 as illustrated in FIG. 3. As can be seen in FIG. 10, thecentre of screw-threaded aperture 45 is displaced from the intersectionof the longer and shorter axis of the oval shaped cross section of bodymember 37. However, the centre of screw-threaded shaft remains on thelonger axis, the reason for which will be discussed in detail below.

In use, both of retaining members 38 are withdrawn from eachscrew-threaded aperture 45 of body member 37 independently of mountingnose 1. Body member 37 is fully inserted into aperture 11 on mountingnose 1 of an excavator bucket as shown in FIG. 3, FIG. 4 and FIG. 5.Adaptor 12 is then located on mounting nose 1. As seen in these figures,aperture 15 on adaptor 12 is partially misaligned with aperture 11 onmounting nose 1 when adaptor 12 is located on mounting nose 1. Thispartial misalignment captively retains body member 37 within aperture 11while mounting nose 1 is located on adaptor 12. Furthermore, body member37 is prevented from rotating within aperture 11 due to the oval shapedcross section of body member 37 being complementary with oval shapedaperture 11.

Referring specifically to FIG. 4 and FIG. 5, even though body member 37is captively retained within aperture 11 due to the misalignment ofaperture 11 and aperture 15, screw-threaded aperture 45 of body member37 is still not covered by adaptor 12 and hence remains accessible. Thisis due to screw-threaded aperture being offset from the centre of bodymember 37 as described above.

To retain adaptor 12 on mounting nose 1, retaining members 38 areinserted through apertures 15 and 11 at opposite ends of body member 37such that the screw-threaded shaft 41 of each retaining member iscoupled with the screw-threaded aperture 45 at either end of the bodymember 37. When tapered shoulder portion 40 abuts tapered recess 44, atleast some of head portion 39 is located within aperture 15 on eitherside of adaptor 12. This protrusion of the head portion 39 at either endof lock 36 prevents adaptor 12 from sliding off mounting nose 1. Asdiscussed above, lock 36 may be used with only a single retaining member38 to retain adaptor 12 on mounting nose 1.

To remove adaptor 12 from mounting nose 1 retaining members 38 aredecoupled from body member 37. This is facilitated by removingscrew-threaded shaft 41 of each retaining member 38 from screw-threadedaperture 45 at either end of body member 37. Adaptor 12 can then beremoved from mounting nose 1 as head portion 39 of each retaining member38 no longer retains the adaptor on the mounting nose. Once adaptor 12has been removed, body member 37 can be extracted from aperture 11.

Lock 36 is self-locking and self-aligning due to the abutment of taperedshoulder portion 40 with tapered recess 44. This tapered contactprovides for greater frictional gripping between body member 37 andretaining member 38 than a conventional square shouldered contact. Aperson skilled in the art will recognise the analogy between the taperedcontact made between retaining member 38 and body member 37 and theconfiguration of a wheel nut. Hence, retaining member 38 remains insecure contact with body member 37 while in use and retains adaptor 12on nose 1. When it is necessary to remove adaptor 12 from nose 1 thetapered contact provides for an easy release of retaining member 38 frombody member 37 thus reducing the time necessary to change the adaptorleading to increased efficiency.

Furthermore, the tapered contact accounts for manufacturing tolerancesof member 37 and retaining member 38 as the lock is self-aligning whentapered shoulder portion 40 proceeds into tapered recess 44, and theretaining member is tightened, the tapered contact guides retainingmember 38 and body member 37 into alignment.

The tapered contact also prevents the passage of water withinscrew-threaded aperture 45 and hence reduces the risk of corrosion oflock 36 although, preferably, an anti-corrosive grease would still beapplied to the components of lock 36 to ensure that no corrosion occurs.

The contact between tapered shoulder portion 40 and tapered recess 44also allows for the efficient transfer of any load on head portion 39 tobody member 37 rather than to the thread of screw-threaded shaft 41.Hence, the only means by which lock 36 may fail is if head portion 39 issheared from screw-threaded shaft 41 and it is envisaged that such aforce will not be encountered in normal operation.

Lock 36 provides for an elegantly simple system for releasably retaininga wear member to a mounting nose of an excavator bucket. The lock isrelatively cheap to manufacture and is easy to use in the field whilestill providing a secure attachment means.

While resilient plugs may be employed to plug the locking pin aperturesof FIGS. 2 to 6 to stop ingress of particulate matter which mightotherwise constitute an abrasive material, entry of dirt into the smallspaces between the flat faces of the socket and spigot members of theassembly tend to pack tightly and actually prevent relative movementbetween the nose and the wear member thus reducing, rather thanincreasing, internal wear between components.

Throughout this specification, unless the context requires otherwise,the word “comprise”, and variations such as “comprises” or “comprising”,will be understood to imply the inclusion of a stated integer or groupof integers or steps but not the exclusion of any other integer or groupof integers.

This invention has been described in detail with reference to specificembodiments thereof, including the respective best modes for carryingout each embodiment. It shall be understood that these illustrations areby way of example and not by way of limitation.

1. An excavator tooth system comprising: a mounting nose having aprojecting spigot; and, a wear member having at one end thereof asocket, said socket being defined by spaced side walls and upper andlower walls converging from a rearwardly facing socket opening to aforward end of said socket, each of said upper and lower wallsrespectively comprising a planar front socket bearing face and a planarrear socket bearing face separated by a forwardly convergentintermediate face, said front and rear socket bearing faces beingsubstantially parallel to a longitudinal axis of said wear member, saidmounting nose having complementary planar front and rear spigot bearingfaces on upper and lower surfaces thereof, said front and rear spigotbearing faces being substantially parallel to a longitudinal axis ofsaid mounting nose and, in use, snugly engaging with said front and rearsocket bearing faces when said wear member is located on said mountingnose.
 2. A system as claimed in claim 1 wherein said forward end of saidsocket forms an end bearing face.
 3. A system as claimed in claim 2wherein said end bearing face extends transversely of said longitudinalaxis.
 4. A system as claimed in claim 1 wherein the wear membercomprises an adaptor having a front end adapted for releasableattachment thereto of a digging point.
 5. A system as claimed in claim 1wherein said wear member includes an aperture in at least one wall ofsaid socket.
 6. A system as claimed in claim 1 wherein said wear memberincludes aligned apertures on opposite walls of said socket.
 7. A systemas claimed in claim 6 wherein said aligned apertures extend throughopposite side walls of said socket.
 8. A system as claimed in claim 1wherein at least portion of said rear bearing face is of a width greaterthan said forward bearing face.
 9. A system as claimed in claim 1wherein at least portion of said rear bearing face is of a substantiallya similar width to said forward bearing face.
 10. A system as claimed inclaim 1 wherein said rear bearing face is of an area greater than saidforward bearing face.
 11. A system as claimed in claim 1 wherein saidsocket opening has a transverse width greater than the width of theforward end of said socket.
 12. A system as claimed in claim 1 whereinthe side walls of said socket taper convergently towards said forwardend of said socket.
 13. A system as claimed in claim 12 wherein saidside walls taper convergently at an angle of from 8° to 11° relative tosaid longitudinal axis of said wear member.
 14. A system as claimed inclaim 13 wherein said side walls taper convergently at an angel of about11°.
 15. An excavation device having an excavator tooth system accordingto claim
 1. 16. An excavation device as claimed in claim 13 wherein saidmounting nose is attached thereto.
 17. An excavation device as claimedin claim 13 wherein said mounting nose is integrally formed therewith.